ニッケルあるいはパラジウムを少量添加したＭｏ合金の低温破断挙動

Abstract

Three-point bend tests were performed for five kinds of molybdenum-nickel alloys and three kinds of molybdenum-palladium alloys. After correcting for the grain size effect, the critical stress and critical temperature representing the low-temperature fracture strength and ductility of the material, respectively, were evaluated. First, effects of a small addition of nickel or palladium on the low-temperature fracture behaviour of molybdenum were investigated. Secondly, improvement of low-temperature ductility by nickel or palladium additions was discussed in terms of critical stress and yield strength.The results are summarized as follows.(1) The average grain size decreased by nickel or palladium additions.(2) In Mo-Ni alloys and Mo-Pd alloys, the critical stress decreased with the alloy content.(3) In Mo-Ni alloys, the yield strength decreased with the alloy content up to 610 at.ppm, but it tended to increase at the alloy content of 830 at.ppm. In Mo-Pd alloys, the yield strength decreased with the alloy content up to 500 at.ppm.(4) In Mo-Ni alloys, the critical temperature decreased with the alloy content up to 610 at.ppm, but it tended to increase at the alloy content of 830 at.ppm. In Mo-Pd alloys, the critical temperature decreased with the alloy content up to 500 at.ppm.